/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.runtime.io.network.partition;

import org.apache.flink.annotation.VisibleForTesting;
import org.apache.flink.util.Preconditions;

import java.util.Optional;

/**
 * Container for meta-data of a data set.
 */
public final class DataSetMetaInfo {
	private static final int UNKNOWN = -1;

	private final int numRegisteredPartitions;
	private final int numTotalPartitions;

	private DataSetMetaInfo(int numRegisteredPartitions, int numTotalPartitions) {
		this.numRegisteredPartitions = numRegisteredPartitions;
		this.numTotalPartitions = numTotalPartitions;
	}

	public Optional<Integer> getNumRegisteredPartitions() {
		return numRegisteredPartitions == UNKNOWN
			? Optional.empty()
			: Optional.of(numRegisteredPartitions);
	}

	public int getNumTotalPartitions() {
		return numTotalPartitions;
	}

	static DataSetMetaInfo withoutNumRegisteredPartitions(int numTotalPartitions) {
		return new DataSetMetaInfo(UNKNOWN, numTotalPartitions);
	}

	@VisibleForTesting
	public static DataSetMetaInfo withNumRegisteredPartitions(int numRegisteredPartitions, int numTotalPartitions) {
		Preconditions.checkArgument(numRegisteredPartitions > 0);
		return new DataSetMetaInfo(numRegisteredPartitions, numTotalPartitions);
	}
}
